Design and Assessment of a Planar Inductor for a 32-kW High Power Density DC-DC Converter

A uniform-flux inductor (UFI) design strategy is described in this article to improve the gravimetric power density of the common inductor of a 32-kW, 350-V dual-interleaved buck-boost dc-dc converter. The strategy consists of an unusual, enclosed winding arrangement that virtually distributes the core magnetic flux density outcoming in a more compact inductor. The resultant common inductor's weight and volume are reduced by 41% and 24%, respectively, and the power density is increased to 7.9 kW/kg. A COMSOL multiphysics finite-element software (COMSOL) numerical prediction confirms almost uniform flux density distribution along the magnetic core axes. Estimation of the inductance, power losses, and thermal behavior is also analyzed. Construction assessment is described for a 7-mu H, 150-kHz, 180-A inductor, which is experimentally verified in a 350-V, 32-kW prototype. The experiments reveal that the built UFI properly operates ensuring both electrical and thermal stability.